In the wake of Sept. 11, a key piece of FAA technology has become an important weapon in the fight against airborne terror.

After Sept. 11, a key piece of FAA technology was deployed at the Colorado Springs headquarters of the North American Aerospace Defense Command (NORAD). Inside the military agency's Cheyenne Mountain facilities now sits a duplicate version of Explorer, the master tracking system that displays all the commercial aircraft flying across the country at any time.

Communications between the civilian and defense air watchdogs also has been enhanced by a direct phone line. And NORAD personnel are now on-site at FAA headquarters and regional air traffic centers to speed reaction to any emergencies, says Major Barry Venable of NORAD.

But no project aimed at modernizing the FAA's methods of controlling airplane traffic likely would have made a difference to the four doomed flights of Sept. 11, 2001, aviation experts and administration officials say.

The biggest problem that day was more psychological than technological: the assumption that these hijackers, like others before them, would force the planes' pilots to make unscheduled landings, not seize control of the aircraft and turn them into missiles.

Although the FAA has a history of letting projects run well behind schedule, those systems, which allow pilots to change course in flight and give them better options when they take off and land, are designed to improve normal air traffic. They are designed to get regularly scheduled flights to their destinations more efficiently, not cope with hostile takeovers of aircraft.

Not that the FAA is beyond blame in what happened last fall. Security lapses allowed hijackers to get on board planes with box-cutters and knives. And there are technologies that might have made a difference if placed in cockpits, such as location transmitters that can't be turned off.

"Things like that have been bandied about for a long time," says Mary Schiavo, the former Department of Transportation Inspector General who has long criticized the FAA for being too hesitant to mandate new equipment that would improve safety.

A transponder, for instance, makes a plane easier to track because it provides identifying information, in addition to amplifying the signal sent back in response to a radar pulse. Tracking a plane that doesn't want to be tracked also can be done the old fashioned way, by bouncing a signal off the skin of the aircraft. But that is trickier and could involve NORAD, which has been criticized by online magazine Slate for its own slow response in September.

Schiavo points to streaming video from the cockpit as a technological improvement that "would have been truly lifesaving" because authorities could have seen the cockpit being invaded and the pilots killed. But prior to September, pilots opposed the idea, figuring it was meant to check up on them, she says.

Ed Cone has worked as a contributing editor at Wired, a staff writer at Forbes, a senior writer for Ziff Davis with Baseline and Interactive Week, and as a freelancer based in Paris and then North Carolina for a wide variety of magazines and papers including the International Herald Tribune, Texas Monthly, and Playboy. He writes an opinion column in his hometown paper, the Greensboro News & Record, and publishes the semi-popular EdCone.com weblog. He lives in North Carolina with his wife, Lisa, two kids, and a dog.